Bending machine



Dec. 8.1970 1 R. J. zum 3,545,241

BENDING MACHINE.

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United States Patent O' 3,545,247 BENDING MACHINE Raymond John Fazzani, Pawtucket, RJ., assignor to Maclodyne Corporation, East Providence, RJ., a corporation of Rhode Island Filed Oct. 8, 1968, Ser. No. 765,916

Int. Cl. B21d 5/04 U.S. Cl. 72-310 i 11 Claims ABSTRACT OF THE DISCLOSURE t A machine for bending tubular stock includes a cylindrical forming die and a cooperating clamping die that are mounted for rotation on a radius arm. The clamping die is hingedly mounted for rotation about an axis above the forming die and is moved into clamping position by actuation of a piston rod that is coaxial with the forming die. A clamp is slid along ways by a pneumatic cylinder four inches in diameter to engage a depending arm of the clamp die and clamp stock positioned between the clamping and forming dies.

SUMMARY OF INVENTION This invention relates to apparatus for bending machines and more particularly to the head andclamping structure for such machines. While the apparatus of the invention can be employed in forming bends in various types of elongated stock, the structures of the invention have particular utility for bending tubular stock of generally circular cross-section.

In conventional apparatus of the type to which this invention relates for forming a smooth radius bend in stock the stock must be clamped securely during the bending operation and the clamping structure moves along an arc during the bending operation. The apparatus must be reset after a bending operation and care must be taken to avoid damaging the bent stock, for exe p ample through contact with the clamping structure.

Accordingly it is an object of this invention to provide novel and improved stock bending apparatus which facilitates resetting of the apparatus after a bending operation without damage to the stock.

Another object of the invention is to provide a novel and improved stock clamping arrangement in bending apparatus of the` type in which the clamping arrangement travels along an arc about a bending die in the bending operation which clamping arrangement, whenreleased,

`does not contact the bent stock during reset of the apparatus. p

Another object of this invention is to provide a novel `and improved bending machine which incorporates an improved stock forming and clamping assembly which may be easily changed.

Still another object of the invention is to provide a novel and improved clamping arrangement which tends to be self-compensating for above average stock tolerance variations.

Another object of the invention is to provide novel and improved bending machine capable of securely clamping over a short length of stock so that a series of bends may be made close toone another in an eiiicient and effective manner.

Still another object of the invention is to provide a novel and improved clamping structure for use in a stock bending machine which includes a rotatable assembly `of a forming die and a cooperating clamping die which assembly firmly clamps stock over a short length thereof `and eliminates slippage or drag during the bending operation.

A bending machine constructed in accordance with lCe the invention includes a support structure which receives for rotation in a bending or forming die that has a peripheral surface of dimensions conforming to the stock to be bent for receiving that stock. A clamping die structure having a cooperating surface is mounted on said forming die support for rotation therewith by a hinge structure which includes a hinge axis disposed perpendicular to the axis of rotation of said forming die. The clamping die is rotated on said hinge structure from a position outside of the plane of the stock to be bent into juxtaposition with the forming die and secured in that position by a clamping structure mounted for movement on a radius arm structure.

The clamping structure applies clamping pressure to said clamping die in a direction perpendicular to the axis of rotation, and is rotated with the forming die during the bending operation through a path outside the plane of the stock. Thus the radius arm-clamping structure, on release of the clamping die, may be returned to its initial position without interference with the bent stock while that stock remains in contact with the forming die.

In a particular embodiment the clamping die is hinged- 1y mounted for rotation about an axis above the plane of the stock and the radius arm-clamping structure is mounted below the plane of the stock. The forming dieclamping die assembly is a relatively simple yet rugged assembly which may be readily detached from the drive spindle and radius arm structure so that different assembly may be attached to accommodate a different size of stock. A first iluid actuated cylinder moves the clamping die into clamping position and a second larger uid actuated cylinder and mechanical linkage moves the clamping structure towards and away from the clamping die. A third iluid actuatedcylinder and similar mechanical linkage moves a follower die into operative position beside the clamping structure, all three cylinders being actuated at the same time in this embodiment.

The invention provides an improved stock clamping arrangement and control in a bending machine which permits reset of the radius arm while the stock remains in contact with the forming die.

Other objects, features and advantages of the invention will be seen as the following description of a particular embodiment progresses, in conjunction with a drawing, in which:

FIG. 1 is a perspective view of a bending machine constructed in accordance with the invention, showing the forming die and radius arm in a position prior to a bending operation:

FIG. 2 is a top view of the bending apparatus of FIG. 1 showing the radius arm in za rotated position after a bending operation;

FIG. 3 is a sectional View of the bending apparatus shown in FIG. 2 taken along the line 3 3 of FIG. 2;

FIG. 4 is a sectional view of the apparatus taken along the line 4-4 of FIG. 2;

FIG. 5 is a view similar to FIG.. 4 showing the clamping apparatus in an open position;

FIGS. 6-8 are top, side and front views of a forming die structure employed in the apparatus shown in FIG. l; and i FIG. 9 is a perspective `view of a different forming die constructed in accordance with the invention with the cooperating clamp die in an open position.

DESCRIPTION OF PARTICULAR EMBODIMENT The bending machine illustrated in FIG. 1 is of a type suitable for bending tubular, bar or rod stock. The machine includes a base 10 on which a support frame 12 is mounted. On the support frame 12 is abending head structure 14, a stock rotating control 15 and a stock advancing control 16 for advancing stock S along a horizontal plane relative to bending head structure 14. Other controls on the base include start stop controls 18 and control 19 which determines the length of bend.

As indicated in FIGS. 2-5, the bending head structure includes a forming die structure 22 and cooperating clamping die structure 24 which is mounted on a radius arm structure 26 for rotation as a unit with forming die 22. A clamping mechanism including four inch diameter cylinder 28 and linkage elements 30-34 is mounted on the radius arm structure 26 and moves clamping head 36 (which slides in ways 37) against the depending extension arm 38 of clamping die structure 24.

A follower die structure 40* is received in guide 42 which is supported on lixed arm 44. Bracket 46 at the end of arm 44 supports a four inch diameter actuating cylinder 48 at pivot 50. The piston rod 52 of the cylinder 48 is connected to clamp levers 54 which is mounted for pivoting movement on block 56. Link 58 connects levers 54 to the follower die carrier structure 42. The follower die 40 slides in ways 64, 66 in the carrier 42 and is biased to a rearward position (away from forming die 22) by spring 68.

FIGS. 4 and 5 show additional details of the clamping die structure 36. Frame 12 supports a vertical spindle shaft 70 which is mounted for rotation in bearing 72. At the lower end of shaft 70 is secured a sprocket wheel 74 which receives drive chain 76 for driving the shaft in rotation. On top of spindle housing 78 is a bearing plate 80 on which the radius arm 26 is seated. Clamping screw 82 secures arm 26 in place and key 84 provides a drive coupling between shaft 70 and arm 26. A pilot 86 one inch in diameter is received in the upper end of spindle 70.

Seated on the upper surface 88 of radius arm 26 and spindle shaft 70 is a forming die-clamping die assembly (shown in FIGS. 6-8) that includes a base plate 90 (secured to arm 26 by bolts 91) on which is mounted a cylindrical forming die 92 which in this embodiment has a diameter of 21/2 inches. In the peripheral surface of this die is provided a circumferential groove 94 of 1A inch radius which extends 270 around the. forming die 92. In the remaining 90 section of die 92 is secured a rectangular block 96 that has a straight groove 98 disposed as an extension of groove 94. In the upper surface of block 96 are formed two tapped holes 100 to which hinge plate 102 of hinge structure 104 is secured to the top of block 96 to bolts 106.

The cooperating hinge plate 108 of hinge structure 104 s secured to clamp die 24 by bolts 110. That clamp die 24 has a 0.251 inch radius groove 112 of 0.245 inch depth arranged so that the centers of radii of grooves 94 and 112 are aligned by the hinge structure 104. The depending arm 38 of die 24 extends two inches below the center of groove 112 and its clamp surface 114 is one half inch high.

A three-eighth inch diameter shaft (FIG. 116 eX- tends upwardly through the spindle and forming die to which is secured a horizontally extending arm 118 and which receives guide pin 119 and engages the clamp die 24 as indicated in FIGS. 4 and 5. Biasing spring 120, secured between elements 122 and 124, tends to rotate die 24 counterclockwise (as viewed in FIGS. 4 and 5) to an open position. Shaft 116 is moved vertically by a one inch diameter air cylinder 126 secured at the base of spindle 70.

In operation, the stock S to be bent is positioned in the groove 94 of the forming die 92 and air pressure is applied simultaneously to cylinders 126, 28 and 48 to move all the clamping elements into position shown in FIGS. 3 and 4. As the diameter of cylinder 126 is substantially smaller than the diameter of cylinder 28, the clamp die 24 is moved into position shown in FIG. 4 before the clamp block 36 engages surface 114. In that position the stock S is firmly clamped between the forming and clamp dies and the follower die 40 is also in contact with the stock S. Spindle 70 is then rotated and the stock is bent about forming die 92 as clamped by die 38, forming a bend in the stock plane of the configuration of the peripheral surface of forming die 92. When the radius arm 26 has rbeen rotated through the angle corresponding to the desired angle of bend, spindle rotation is stopped and the clamping cylinders 28, 48 and 126 are released. Clamping head 36 and follower die 40 are withdrawn and shaft 116 rises to allow spring to raise clamping die 38 so it is entirely above the plane of the stock S. In this position the stock may be moved forward without removing it from the groove 94 in die 92 and spindle 70 may then return radius arm 26 to its initial position parallel to the follower die clamp structure as indicated in FIG; 1. It will be noted that clamp structure 24 is automatically moved above the plane of the stock by spring 120 and as the clamping and radius arm structures are located below the plane of the workpiece there is not interference during this operation.

A moded forming die-clamping die assembly is shown in FIG. 9. This assembly may be changed merely by removal of the two bolts 91. Clamp structures constructed in accordance with the invention provide suicient clamping force to securely clamp a workpiece over a length as short as one diameter of the workpiece so that a satisfactory bending operation without slippage or drag may be performed.

While a particular embodiment of the invention has been shown and described in detail, various modifications thereof will be apparent to those skilled in the art and therefore it is not intended that the invention be limited to the disclosed embodiment or to details thereof and departures may be made therefrom within the spirit and scope of the invention as dened in the claims.

What is claimed is:

1. In a machine for bending elongated stock,

a bending die having a peripheral surface curved to correspond to the bend desired in the stock,

means for supporting said bending die for rotation,

a clamping die adapted to be positioned in juxtaposed cooperating position with said bending die to clamp a length of stock to be bent against said peripheral surface to prevent slippage of the stock relative to said peripheral surface during rotation of said bending die,

a hinge structure coupling said clamping die to said bending die so that said clamping die rotates with said bending die about the axis of rotation of said bending die,

the hinge axis of said hinge structure being located so that said clamping die may be pivoted about said hinge axis out of the plane of the stock to be bent,

a radius arm structure rotatable about said bending die axis,

and a clamping structure mounted on said radius arm structure for movement along a path towards the axis of said bending die for securing said clamping die in clamping position to clamp stock against said peripheral surface of said -bending die,

said clamping structure and said radius arm structure being disposed outside the plane of the stock to be bent so that, on movement of said clamping structure away from the axis of said bending die, said clamping die may be moved out of the plane of the bent stock and said radius arm structure may be rotated back to its initial position after a bending operation while the stock remains in engagement with said peripheral surface of said bending die.

2. A machine as claimed n claim 1 wherein the hinge axis of said hinge structure is above the plane of said stock and said path of movement of said clamping structure is below the plane of said stock.

3. A machine as claimed in claim 1 and further including first lluid operated means for actuating said clamping structure and second fluid actuated means for moving said clamping die to juxtaposed position relative to said bending die.

4. A machine as claimed in claim 3 and further including control mechanism for actuating said rst and second fluid actuated means in coordinated relation to securely clamp stock against said bending die. I

5. A machine as claimed in claim 1 wherein the axis of said hinge structure is otfset from the plane of the stock to be bent.

6. A machine as claimed in claim 1 wherein the axis of said hinge structure is perpendicular to the axis of rotation of said bending die.

7. A machine as claimed in claim 1 wherein said bending die, said clamping die and said hinge structure are a' unit which is releaseably connected in driving relation to said support means.

8. A machine as claimed in claim 7 and further including an actuating mechanism for moving said clamping die into juxtaposed cooperating position with said bending die.

9. A machine as claimed in claim 8 wherein said actuating mechanism includes fluid operated means for moving said clamping die into said juxtaposed cooperating position and further including a biasing mechanism for moving said clamping die out of the plane of the stock to be bent.

10. A machine for bending elongated stock comprising a forming-clamping die assembly including,

a bending die having a peripheral surface curved to correspond to the bend desired in the stock,

a clamping die adapted to be positioned in juxtaposed cooperating position with said bending die to clamp a length of stock to be bent against said peripheral surface to prevent slippage of the stock relative to said peripheral surface during rotation of said bending die,

and a hinge structure coupling said clamping die to said bending die so that said clamping die rotates with said bending die about the axis of rotation of said bending die,

said hinge structure having a hinge axis perpendicular to the axis of rotation of said bending die so that 6 said clamping die may be pivoted about said hinge axis out of the plane of the stock to be bent,

a drive spindle,

means for attaching said forming-clamping die assembly to said drive spindle,

a radius arm structure secured to said drive spindle for rotation therewith,

a clamping structure mounted on said radius arm structure for movement along a path towards the axis of rotation of said drive spindle ior securing said clamp ing die in clamping position to clamp stock against said peripheral surface of said bending die,

said radius arm structure being disposed outside the plane of the stock to be bent so that, on movement of said clamping structure away from the axis of said bending die, said clamping die may be moved out of the plane of the bent stock and said radius arm structure may be rotated by said drive spindle back to its initial position after a bending operation while the stock remains in engagement with said peripheral surface of said bending die.

11. A machine as claimed in claim 10 and further including lluid operated actuating mechanism including an axially movable actuating rod disposed coaxially with said spindle for moving said clamping die into juxtaposed cooperating position with said bending die and a biasing mechanism for moving said clamping die out of the plane of the stock to be bent.

References Cited UNITED STATES PATENTS 2,306,221 12/ 1942 Parker et al 72-155 1,901,762 3/1933 Meyer 72-154 3,433,042 3/ 1969 Criheld et al. 72-217 2,371,695 3/ 1945 Lancaster 72--156 CHARLES W. LANHAM, Primary Examiner M. I. KEENAN, Assistant Examiner U.S. Cl. X.R. 72-149, 311 

